Title: Deformation of soft crystals in precision polishing

Authors: Yong X. Gan

Addresses: Department of Mechanical Engineering, Fu Foundation School of Engineering and Applied Science, Columbia University in the City of New York, 500 West 120th Street, New York City, NY, 100027, USA; Department of Mechanical, Industrial and Manufacturing Engineering, College of Engineering, University of Toledo, Toledo, OH, 43606, USA

Abstract: Grinding/polishing soft materials typically introduces a layer with residual stresses, which impedes the examination of the original deformation states. In this work, precision polishing procedures consisting of mechanical polishing and electrochemical polishing were used to obtain residual-stress-free surfaces in an annealed copper polycrystal and a copper single crystal. For the polycrystal, mechanical polishing followed by electrochemical polishing were used to show the grain structure and etching pits. The polished single crystal was analysed by electron backscatter diffraction (EBSD) technique to reveal the lattice rotation field related to the original deformation state induced by wedge indentation. Specifically, the geometrically-necessary dislocation density was calculated based on the in-plane crystal lattice rotation angles. The precision polishing makes the observation of the effective slip systems as predicted by the crystal plasticity theory possible. The precision polishing also helps reveal the deformation instability in the indented copper single crystal by sharp indenters.

Keywords: precision polishing; soft crystals; mechanical polishing; electrochemical polishing; deformation states; electron backscattering diffraction; EBSD; lattice rotation field; geometrically-necessary dislocation density; residual stresses; annealed copper polycrystal; copper single crystal; plasticity theory.

DOI: 10.1504/IJAT.2009.024400

International Journal of Abrasive Technology, 2009 Vol.2 No.3, pp.299 - 312

Received: 20 Jul 2008
Accepted: 03 Sep 2008
Published online: 02 Apr 2009 *

Full-text access for editors Full-text access for subscribers Purchase this article Comment on this article